Gangrene and necrosis are two different terms that are perhaps not very common to hear from non-medical people. Given the fact that they are different pathologies , which people often confuse; It is important to clarify some of the basic differences, just in case and it happens to you or one of your loved ones.
After extensive tissue injury, doctors can use these terms to explain things to you. Sometimes it is very difficult to explain, because they are complex processes with multiple important stages; which is why health professionals use terms such as necrosis or gangrene to refer to the entire process.
The first thing you should know is that there are several types of necrosis and that gangrene is one of those types. Necrosis can occur directly or after cell degeneration. The first changes are very subtle and appear in the electron microscope only after 2 or 3 hours and in the light microscope only after 6 hours. Cellular changes can be divided into nuclear and cytoplasmic changes. Nuclear material can clump into dense masses that cause staining, this is known as “pyknosis”; These clumps can later be divided into small particles in a process known as “karyorrhexis.” Cytoplasmic changes begin in the cytoplasm and create acid spots; this is due to denaturation of cytplasmic proteins. The special organelles absorb water and swell.
There are many types of necrosis: coagulative necrosis, liquefaction necrosis, fat necrosis, caseous necrosis, gummy necrosis, fibrinoid necrosis, and gangrene. Coagulative necrosis is commonly seen in solid organs after insufficient blood supply. In liquefaction necrosis the cell is completely smoothed out, so there is no cell contour, this is commonly seen in the brain and spinal cord. There are two types of fat necrosis, enzymatic and non-enzymatic. In enzymatic fat necrosis, a chalky white appearance is created, whereas non-enzymatic fat necrosis is seen mainly in the subcutaneous tissue, chest and abdomen. Patients with nonenzymatic fat necrosis almost always have a history of trauma. Caseous and gummy necroses are due to the formation of granulomas after infections. Fibrinoid necrosis is commonly seen in patients withautoimmune diseases .
Gangrene is a term widely used to refer to a clinical condition where necrosis of the tissues spreads that is complicated to varying degrees by a secondary bacterial infection. There are three types of gangrenas; dry, wet and gaseous gangrene. Dry gangrene occurs mainly in the extremities, due to the lack of blood supply that results from clogged arteries. Wet gangrene is the result of a severe bacterial infection superimposed on necrosis. It can occur in the extremities as well as internal organs. Moist gangrene is difficult to delineate from adjacent healthy tissue, therefore surgical excision is difficult. The mortality rate in wet gangrene is high.
Gas gangrene is due to infection with Clostridium perfringens. It is characterized by extensive necrosis and gas production. There is crepitus on palpation.
Key differences between gangrene and necrosis
- Necrosis can occur without infection, whereas gangrene is due to infection of necrotic tissue.
- Gangrene is generally more extensive than necrosis.
- Mortality from gangrene is higher than from necrosis.